Captain Syrup and Wario Land in general is so underrated. If only Captain Syrup was the Wario rep everyone was rallying behind because she could bring so much more to the table than any Warioware character in my opinion.
Been saying this, everyone is always talking about the lack of Wario Land content in the game but not enough people are pushing for the most prominent character from that series (other than the man himself, obviously). There's no reason why Syrup couldn't happen as a result of a dedicated fan push in the same way K. Rool was revived, I really want to see that movement happen and I'll be at the forefront of it when it does.
With Syrup you have the opportunity to bring definitive Wario Land content without pointlessly shouting at Sakurai to change a unique (and fun!) moveset - considering he has a tendency to stick with his guns and keep characters the way they were already established more or less. I'd like a couple more Wario Land moves on Wario as much as the next guy but yknow, maybe if there was more effort put behind rallying for a new vessel for more Wario Land content that would happen regardless. I think Wario is perfectly fun as is too, so no major issue one way or the other for me.
Also Captain Syrup rocks. Awesome design and the more pirates in Smash the better.
Not to disparage any Warioware characters though because I think a bunch of them would be great too. I wouldn't be disappointed to get say, Mona or Ashley instead of Captain Syrup - but I think Syrup is the best possible option of the bunch.